Windmills are seen as a source of green energy, but researchers say they pose a threat to wildlife in forests through collisions and noise.
The impact of the giant structures in Karnataka was studied by researchers from Salim Ali Centre for Ornithology and Natural History (SACON) during a two-year project. They found that windmills killed birds and bats in collisions, and that birds and mammals also moved away due to the noise.
The noise levels near windmills go up to 85 decibels (dB), the equivalent of large trucks. The drone of a turbine, which operates day and night, is above 70dB. By comparison, noise in urban areas is 55 dB and even in industrial areas, is lower at 75dB. Ambient noise in forests is less than 40 dB.
Such avoidance and movement to [forest] fringes might increase conflict with humans. This calls for protocols and policy guidelines before diverting forest land for wind farms, states the study funded by Karnataka Forest Department, Karnataka Renewable Energy Development Limited (KREDL) and National Institute of Wind Energy.
Karnataka has diverted 37.80 sq. km of forests for wind farms, Union Environment Ministry data show. KREDL says that there are more than 3,857 wind turbines generating 4,730 megawatts of electricity.
The researchers led by H.N. Kumara looked at windmills in Chitradurga (around Jogimatti forests) and Gadag, including Kappatagudda, which was recently declared a sanctuary. They recorded between 35% and 40% of Karnataka’s bird diversity in these areas.
In a short span
The team saw collisions of 10 animals – 6 bats and four birds – with a collision rate of 0.23 animals per year per turbine. While the collision rate was low compared to other locations, it could not be ignored as the bulk of them took place in a short span of time, the study says.
Researchers found birds avoiding windmill sites. “There are 50% fewer birds in the areas compared to undisturbed sites,” says Dr. Kumara. The avoidance is seen among mammals too. Herbivores moved away, with predators following them. “This area is perhaps the only one where three types of antelopes are found: four-horned, chinkara, and blackbuck. And all these are moving away towards fringes of forests. Following them are predators such as wolves and small carnivores. This is bound to increase conflict,” says Dr. Kumara. For certain small herbivores such as hare, the predator-free patches represented safety.
On the study results, C. Jayaram, Principal Chief Conservator of Forests (Wildlife) said, “We have asked for certain refinements, and we will look seriously at the impact of windmills on birds and mammals. We will draw up guidelines for windmills to mitigate these effects.”